const int CURRENT_PIN = A0;
const int TEMP_PIN = A1;
const int RELAY_PIN = 7;
const int BUZZER_PIN = 8;
const int RESET_PIN = 2;

const int RELAY_ON = HIGH;
const int RELAY_OFF = LOW;

const float CORD_RATING = 10.0;  // amps
const float TEMP_LIMIT = 60.0;   // degrees C
const float BETA = 3950.0;

bool tripped = false;

float readCurrent() {
  return analogRead(CURRENT_PIN) * 15.0 / 1023.0;  // 0 to 15 A
}

float readTemp() {
  int raw = analogRead(TEMP_PIN);
  return 1 / (log(1 / (1023.0 / raw - 1)) / BETA + 1.0 / 298.15) - 273.15;
}

void setup() {
  Serial.begin(9600);
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(RESET_PIN, INPUT_PULLUP);
  digitalWrite(RELAY_PIN, RELAY_ON);  // power ON at start
}

void loop() {
  float current = readCurrent();
  float temp = readTemp();

  // Trip if overloaded or too hot
  if (current > CORD_RATING || temp > TEMP_LIMIT) {
    tripped = true;
  }

  // Cut power and sound the buzzer
  if (tripped) {
    digitalWrite(RELAY_PIN, RELAY_OFF);
    digitalWrite(BUZZER_PIN, HIGH);
  }

  // Reset only works when the cord is safe again
  if (tripped && digitalRead(RESET_PIN) == LOW &&
      current <= CORD_RATING && temp <= TEMP_LIMIT) {
    tripped = false;
    digitalWrite(RELAY_PIN, RELAY_ON);
    digitalWrite(BUZZER_PIN, LOW);
  }

  Serial.print("Current: ");
  Serial.print(current);
  Serial.print(" A | Temp: ");
  Serial.print(temp);
  Serial.println(tripped ? " C | TRIPPED" : " C | OK");
  delay(500);
}